Classic mag leak. Please Help.

[athomas]

So I just got a 68 classic in the mail I got through a trade. Excited to use it, I hook up the co2 tank and air pours down the barrel violently. I took it apart and gave it a good oiling and tried again with no luck. If I hold the trigger down the leak stops. I've replace all the orings in the on/off and checked the orings in the power tube, but they look fine. I don't have a parts/ seal kit yet so i'll be ordering one as soon as I get paid next week. Another thing I have noticed is that when I let go of the trigger the bolt comes forward about 1/8".
If I push back on the bolt when it is leaking with my finger, the leak also stops. Ive got a level 7 bolt if that helps. I don't know if maybe I need a stronger bolt spring or what. I've just kind of hit a wall in my trouble shooting. I'm new to classics, so I don't really know what else to look for. I have never encountered a problem like this in my other mags. Thanks in advance for your help.

If the bolt moves 1/8", when you release the trigger, check that the rail bushing is in place.

Operationally, your mag valve is doing what it is supposed to do. When you hold the trigger, it does not leak. There is no air in the front chamber and the bolt spring holds the bolt in the back position. When you release the trigger, the sear rotates up to hold the bolt and the on-off opens to fill the front chamber with air which pushes the bolt forward against the sear. Generally, the forward movement is much less than 1/8", but if the sear is worn or the bumper is missing, that could account for a longer movement. When the bolt is held in place by the sear, the bolt stem will be resting against the powertube oring effectively sealing the front chamber from leaking air. If the powertube spacer is too long or if the sear is worn, the bolt will sit too far forward to seal properly. Usually there is not enough tolerance to allow 1/8" of movement in the bolt from the rear position to the position where it is being held by the sear. The fact that there is this much movement usually means something is missing or out of tolerance.

Check that your rail bushing is in place
Check the condition of your bumper
Check your sear for wear
Use a shorter powertube oring

[Timber_Ghost]

installed my new sear and pin today. marker is shooting like a champ. Thanks for your help everybody. Its been informative.

[athomas]

Thanks for the update. By posting the fix it helps others that may have the same issues.

Good to hear you you got it working. :)

[Timber_Ghost]

Thats why I did it. Its frustrating when you read a tech thread and have no idea what was actually wrong whith the marker.